Process of manufacturing plastic asphaltic compositions for pavements



Patented July 21, 1931 UNITED STATES PATENT OFFICE FREDERICK C. ALSDORF,OF CHICAGO, ILLINOIS PROCESS OF MANUFACTURING PLASTIC ASPHALTICCOMPOSITIONS FOR PAVEMENTS No Drawing.

This invention relates to an improvement 1n the method of mlxmg certamasphaltic compos1t1ons that are now in commercial use in the layin ofroads,

streets, walks, 7 driveways, etc. whereby the mixed asphaltic roadmaterial maybe more easily unloaded from railroad cars, shoveled out ofpiles, spread upon roadways.

and

This invention is limited to those asphaltic p compositions which aremixed at'a temperature less than the boiling point of water. Suchcompositions contain a mineral aggregate, a fluxed asphalt and aliquefier.

liquefier is defined as a liquid hydrocarbon which will volatilize onexposure to air, within a period of two years ina roadway.

The

' liquefier maybe added to the asphalt before it is mixed with theaggregate or the liquefier may be added to the aggregate before heatedasphalt is added or the liquefier may be added to a mixture of aggregateand hot asphalt. The above processes are now in use and my invention isconfined solely to an im' provement in the method of mixingtheconstituents in the above processes.-

Such compositions depend onthe evaporation of their volatileconstituents for their setting uppower.

The control of this hardin cool weather.

On the other hand such a comparatively high percentage of liquefier inthe asphalt makes it impossible to keep enough asphalt on the separateparticles of aggregate to insure a lon severe tra c .and weatherconditions.

life to the composition under The Application filed October 1 5, 1928.Serial No. 312,738.

thinned asphalt may run through truck loads of mixed material orthroughthe bottom of loaded railroad cars, thus decreasing the percentage ofthe original mixtures. The setting up process is delayed and thecomposition may be so thin that it will spread out under a roller andtrafiic.

Vi-ch my improved method it ispossible to use the minimum quantity ofliqu'efier required to flux the asphalt or to coat the stone previous toor subsequent'to the addition of hot asphalt, at the same time anyamount of asphalt can be added to the aggregate, depending on itsgrading, as to insure a proper degree'of thickness of coating. v Myimproved method of handling is at tained by adding a smallamount ofWater with an emulsifying agent assoap, clay, and the like to'themixture, while it is being made.

A hydrocarbon emulsion can also be used.

The effect is to produce a slight emulsification of the asphalt on thesurface of each separate particle. This emulsification is not sufiicientto prevent the packing action of a roller or traflic upon the mixedmaterial when spread on a roadway. Only enough emulsi-' fying agent isadded to emulsify but a small part of the asphalt in the mixed material.

The general effect, until the water has evaporated, is to reduce theductility and tenaciousness' of the asphaltbinder permitting the mixedmaterial to be handled and spread much more easily than if no partialemulsification has been produced. After the water has evaporated, theoriginal ductility and tenacity are restored to the asphalt binder.

In cool weather the effect of the slight emulsification in the mixtureis more pron unced. At temperatures of 50 degrees Fahrenheit it isimpossible with some standard mixtures to unload railroad cars filledwith asphaltic material, not emulsified in any way, without resorting toheating the set up, mixed material by steam, while with identically thesame material partially emulsified o g V the unloading 7 heating.

- emulsion.

is accomplished easier with no On account of the packing action of apile of mixed asphaltic composition I have found that water is retainedin the pile for some time and that the emulsified efiect is retaineduntil the water has entirely dried out.

Without limiting myself to these proportions or the material employed Ihave found the following mixtures tongive good results:

1. An improved method of producing asphaltic compositions whichcomprises add ing to a cold mix asphalt composition oomprising aggregatecoated with asphalt fluxed with a liquefier normally used in the art,ajsmall amount of Water and an emulsifying agent to produce a partialemulsification only of the asphalt largely on the surfaces of theasphalt coated particles of mineral matter.

2. An improved method of producing asphaltic compositions whichcomprises adding to a cold mix asphalt composition comprising aggregatecoated with asphalt fluxed with a .liquefier normally used in the art, asmall amount of a hydrocarbon FREDERICK o. ALSDORF.

